X-ray trigonometric parallax/Laboratory

This laboratory is an activity for you to perform X-ray trigonometric parallax on a star, or other nearby X-ray source of your choice using its X-ray characteristics. While it is part of the astronomy course principles of radiation astronomy, it is also independent.

For determining an X-ray trigonometric parallax of your star or other nearby X-ray source, what would make an acceptable control group? Think about a control group to compare your determination of your star or your process of determining its parallax to.

Trigonometric parallax may be somewhat wavelength dependent. Usually, it depends on resolution and using a periodic set of measurements where the diameter of the period is large enough to allow resolution. To attempt X-ray trigonometric parallax, a candidate star that is within resolution of at least one currently available or formerly available X-ray satellite is needed. If none qualify for even the closest star, then a calculation that is time based may work or a calculation using a greater periodic set is needed.

For the effort to succeed a collection of three to five very distant, unmoving X-ray sources must be available to determine the target's relative movement.

Since the idea of using X-ray astronomy satellites is novel and perhaps a bit premature, finding a relatively nearby source where the experiment may be performed may be itself a time-consuming task too soon for a course.

To test even this hypothesis, I choose Proxima Centauri.

According to SIMBAD, V645 Cen (Proxima Centauri) is an X-ray source in the catalogs: 1E, 2E, 1ES, RE, RX, 1RXS, and [FS2003]. Catalogs 1E through 1ES are the Einstein satellite observations. Catalogs RE through 1RXS are the ROSAT satellite observations. Catalog [FS2003] is a systematic search for variability among ROSAT All-Sky Survey X-ray sources by B. Fuhrmeister and J. H. M. M. Schmitt in an article published in Astronomy and Astrophysics.

The visual astronomy parallaxes (mas) on Proxima Centauri are 774.25 ± 2.08, according to SIMBAD. As the resolution of neither Earth-orbit satellite is within the parallax range it is unlikely that any sets of X-ray observations from these two satellites can resolve parallax movement by Proxima Centauri.

Perhaps one of the current X-ray satellites has sufficient resolution:

This is a Chandra X-ray Observatory image of Proxima Centauri. Credit: NASA/CXC/SAO.

"Chandra and XMM-Newton observations of the red dwarf star Proxima Centauri have shown that its surface is in a state of turmoil. Flares, or explosive outbursts, occur almost continually. This behavior can be traced to Proxima Centauri's low mass, about a tenth that of the Sun. In the cores of low mass stars, nuclear fusion reactions that convert hydrogen to helium proceed very slowly, and create a turbulent, convective motion throughout their interiors. This motion stores up magnetic energy which is often released explosively in the star's upper atmosphere where it produces flares in X-rays and other forms of light."[3]

"The same process produces X-rays on the Sun, but the magnetic energy is released in a less explosive manner through heating loops of gas, with occasional flares. The difference is due to the size of the convection zone, which in a more massive star such as the Sun, is smaller and closer to its surface."[3]

"Red dwarfs are the most common type of star. They have masses between about 8% and 50% of the mass of the Sun. Though they are much dimmer than the Sun, they will shine for much longer - trillions of years in the case of Proxima Centauri, compared to the estimated 10 billion-year lifetime of the Sun."[3]

"X-rays from Proxima Centauri are consistent with a point-like source. The extended X-ray glow is an instrumental effect. The nature of the two dots above the image is unknown - they could be background sources."[3]

Many and almost 50% of all X-ray sources have no visual counterpart. These sources may be nearby clouds, hidden stars, or others. Being able to perform X-ray trigonometric parallax would go a long way to determining where and what these sources are. Assessment of the possibility to perform X-ray trigonometric parallax on the nearest X-ray star after the Sun has been performed to determine the apparent state of the art.

Introduction

Of the many X-ray sources in various databases such as SIMBAD, few sources have visual counterparts. Fewer yet have any distance measurements available. With so many stand-alone X-ray sources, it would be worthwhile to assess current X-ray observatory capability for trigonometric parallax.

Experiment

A sampling of X-ray observatories past and current that may have or be capable of performing X-ray trigonometric parallax on Proxima Centauri has been assessed.

Results

At present it appears that no X-ray observatory can or has performed X-ray trigonometric parallax on Proxima Centauri. The Chandra X-ray Observatory may be able to yield a range but has only perceived Proxima Centauri as a point source. Within a 20 arcminute radius of Proxima Centauri there are four known X-ray sources that may be far enough away to be used as parallax immobile X-ray sources, according to SIMBAD.

Discussion

Although an assessment of time-based observations over a multi-year time-frame may show that X-ray trigonometric parallax of a selected target is possible, this may be more time-consuming than productive at this point. An expanded orbit approach using say the Chandra X-ray Observatory at its orbital extremes while at semi-annual Earth orbit extremes is unlikely to increase the resolution significantly.

Conclusion

Current and former X-ray observatory satellites have been in orbit around the Earth since the seventies (1970s) yet it forty years of research apparently not one of these technologies has been developed to permit X-ray trigonometric parallax of any object outside the solar system.

To assess your X-ray trigonometric parallax calculations of the star of your choice, including your justification, analysis, results, and discussion, I will provide such an assessment of my example for comparison.

Evaluation

The time necessary to assess other X-ray sources such as Jupiter has not been applied. The Sun could have been used to assess the capability of the technology with the GOES satellites.